This invention relates to controllable pitch propellor arrangements for energy conversion between electrical energy and fluid energy.
Controllable pitch control of propellers or turbine blades is commonly used to improve operating efficiency and flexibility particularly in the marine industry. For such applications, conventional controllable pitch propellers or turbines have blades mounted on a hollow support shaft and include a complex actuation mechanism extending through the hollow shaft. Typical arrangements for rotating the blades of this type are disclosed in U.S. Pat. Nos. 3,785,747 and 4,648,345.
Also, shaftless pumps are known in various industries in which propellor blades are affixed to a driven rim. This provides the advantage of reducing restriction or disruption to the flow of fluid to the propeller blades which can occur when the blades are driven by a propellor shaft. Such arrangements are disclosed in U.S. Pat. Nos. 3,708,251; 3,914,629; 4,831,297; 5,185,545; 5,252,857 and 5,306,183.
U.S. Pat. No. 2,909,229 discloses a reversible pitch fan having fan blades connected to two rims which can be angularly shifted between two positions by stressing the blades or the rims to reverse to the blowing direction of the fan to remove dust and debris from radiators. The blades are retained in either of the two positions by resilience of the blades or the rims.